First, there's the application version. The current (latest) version is 4.7.

Then for each application version, there's different installation packages, and different languages.

There are really only two installation packages - one with, and one without Media Manager. I recommend a version without Media Manager. It doesn't play well with either Vista, or any machine that already has any Roxio products already installed. Also, the download size of packages without Media Manager are about 200 Megs smaller than the comparable version with it, and saves almost double that in disk space when installed.

Finally, there are Multilanguage and single language packages. If you know you'll only need a single language, this will save you about 30 Megs in the download size, and probably about the same or double that on the installation.

As for your second question, the more you install on a BlackBerry, the slower it will run - not by much, but it will eventually become noticeable. Uninstalls are generally pretty thorough, but as with any computer, wiping it clean and reinstalling from scratch is always cleaner and faster.